<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			*{
				margin: 0;
				padding: 0;
			}
			.nav{
				width: 100%;
				height: 40px;
				background-color: rgba(255, 0, 0, 1);
				text-align: center;
			}
			.search{
				width: 100%;
				height: 20px;
				background-color: rgba(0, 0, 0, 0.3);
				text-align: center;
			}
			.section{
				width: 100%;
				height:300px;
				background-color: rgba(0, 0, 255, 0.2);
				text-align: center;
			}
			.center{
				width: 1000px;
				height: 100%;
				background-color: aqua;
				margin: auto;
			}
			
			
			
			
		</style>
	
	</head>
	<body>
		
		<div class="nav">
			<div class="center">
				导航
			</div>
			
		</div>
		<div class="search">
			<div class="center">
				搜索
			</div>
			
		</div>
		<div class="section">
			<div class="center">
				主体
			</div>
			
		</div>
		
	</body>
</html>